Long before Door County’s forests, farms, and shorelines existed, the peninsula lay beneath a warm, shallow tropical sea teeming with life. Corals, crinoids, brachiopods, and other marine organisms thrived here hundreds of millions of years ago, leaving behind the fossils that can still be found embedded in Door County’s dolomite bedrock today. This week’s Summer at Crossroads theme, Fossils, invites visitors to uncover clues from Earth’s distant past and explore the ancient history hidden beneath our feet.
The week begins with a Tale. At 2 pm on Monday, August 17, “Curious About Fossils” by Kate Waters will be read aloud to participants. This engaging book introduces young readers to the fascinating world of fossils, explaining how they form and what they reveal about ancient life on Earth. Along the way, readers will meet famous fossil hunters such as Mary Anning, who discovered the first ichthyosaur skeleton; Richard Owen, who coined the word “dinosaur”; and Barnum Brown, who uncovered the first remains of a T. rex. The story also explores how modern scientists use technology to uncover clues from fossilized bones, teeth, and even footprints. For those unable to attend Story Time, the book will also be featured on our Trail Tales storybook walk, available all week long beginning at the West Trailhead.
At 1 pm on Tuesday, August 18, Journeys with Joan will explore Finding Fossils. Naturalist Joan Wilkie will guide participants in discovering how plants and animals from an ancient sea became the fossils we find throughout Door County today. Visitors will learn how fossils form over vast stretches of time and gain a deeper appreciation for the marine life that once inhabited the region. As participants examine examples and explore fossil-rich landscapes, they will better understand the geological history that shaped the peninsula we know today.
On Wednesday, August 19, at 1:30 pm, participants in Wandering Wednesday will join a naturalist-led hike to look for evidence of Door County’s geological past. Along the trails, hikers will explore the landscape with fresh eyes, observing rock formations, exposed dolomite, and features influenced by ancient seas and glacial activity. The hike will highlight the connections between geology, fossils, and the modern ecosystems that have developed atop this ancient foundation.
The week concludes with a special Talk at 2 pm on Thursday, August 20. We welcome back Naturalist Coggin Heeringa, who will present Ancient Silurian Seas, a fascinating journey back hundreds of millions of years to a time when Door County was covered by a warm, shallow sea. Participants will discover how coral reefs, marine invertebrates, and other sea life flourished here during the Silurian Period, long before dinosaurs or even land plants existed. The program will explore common local fossils such as corals, brachiopods, and crinoids, explaining how they formed, where they can still be found today, and what they reveal about changing climates and environments through time. Coggin will also connect these fossils to Door County’s distinctive dolomite bedrock, Niagara Escarpment, and shoreline landscapes, helping participants understand how the peninsula’s ancient past continues to shape the present.
Throughout the week—and continuing year-round during open hours—visitors can also enjoy Tinkers, our self-led, hands-on activities designed for curious minds. Guests can examine fossils, investigate ancient life forms, and explore the processes that preserve traces of organisms for millions of years.
Fossils are more than remnants of long-extinct organisms; they are records of ancient environments and evidence of dramatic changes across Earth’s history. In Door County, fossils remind us that our familiar landscape was once a tropical sea filled with life very different from what we see today. By exploring fossils, we gain a deeper understanding of the forces that shaped our region and a greater appreciation for the immense span of time recorded in the rocks beneath our feet.
Thanks to the generosity of our donors, we can offer free programming for all ages, and our trails are open all day, every day, free of charge.
Monday, August 17
2:00 pm — Tale: “Curious About Fossils”
Join us as our weekly story, Curious About Fossils, written by Kate Waters, is read aloud.
Aren’t you curious about what Earth was like long ago? What creatures lived before us? What happened to the dinosaurs?
Curious About Fossils explains why and where fossils form and looks at the colorful lives and important discoveries of some of the great early fossil hunters and collectors, including Mary Anning, who unearthed the first ichthyosaur skeleton; Richard Owen, who coined the word “dinosaur”; and Barnum Brown, who discovered the first remains of a T. rex. Then the adventure continues into modern times, when scientists on fossil hunts in places like North Dakota’s Hell Creek Formation use computers and other technology to dig up the fossilized bones, teeth, and even poop that provide clues to the past. Meet at the Collins Learning Center, Crossroads at Big Creek, 2041 Michigan Street, Sturgeon Bay.
Tuesday, August 18
1:00 pm — Journeys with Joan – Finding Fossils
Join our naturalist, Joan Wilkie, for free family-oriented activities exploring nature!
Discover how plants and animals from an ancient sea transformed into the fossils we find at Crossroads. Registration is not required. Open to the public and free thanks to donors like you! Meet at the Collins Learning Center, Crossroads at Big Creek, 2041 Michigan Street, Sturgeon Bay.
Wednesday, August 19
1:30 pm — Wandering Wednesday
Join a naturalist-led hike. Easy walking. About an hour. Well-behaved dogs are allowed on leash. Registration is not required. Open to the public and free. Meet at the Collins Learning Center, Crossroads at Big Creek, 2041 Michigan Street, Sturgeon Bay.
Thursday, August 20
2:00 pm — Talk: Ancient Silurian Seas
Travel back hundreds of millions of years to a time when Door County was covered by a warm, shallow sea! Join Naturalist Coggin Heeringa for a fascinating program exploring the ancient Silurian seas and the fossils they left behind.
Coggin will guide participants through Door County’s deep geological past, explaining how coral reefs, marine invertebrates, and other sea life flourished here during the Silurian Period—long before dinosaurs or even land plants existed. Learn how fossils such as corals, brachiopods, and crinoids formed, where they can still be found today, and what they reveal about Earth’s changing climate and environments over time.
This accessible and story-rich program will help you recognize common local fossils and understand their connection to Door County’s distinctive dolomite bedrock, escarpment, and shorelines. Perfect for curious beginners and seasoned rockhounds alike, this talk brings ancient geology to life through science, history, and hands-on discovery.
Join us to uncover the fossilized remains of a long-vanished sea and gain a deeper appreciation for the ancient forces that shaped the peninsula we know today. Meet at the Collins Learning Center, 2041 Michigan Street, Sturgeon Bay.
